Recent reform in K-12 science advocates for fostering a new type of integrated knowledge, where disciplinary ideas are learned through the practices of scientists and engineers. Moreover, when fostering this knowledge, the reform emphasizes the need to illuminate to students the practices of scientists and engineers and to promote learning by making learning relevant to students’ lives. In this talk I will present my dissertation research that addressed the reform’s vision in the context of classroom formative assessments. The dissertation explores the design of an online assessment called the 4R Activity. Similar to scientists and engineers, students in the 4R Activity built knowledge products by receiving and providing double-blinded reviews and using the reviews to revise their products. I will report on the findings pertaining to (a) students’ achievement outcomes; (b) the quality of the products generated during the 4R Activity; and (c) students’ perspectives on the 4R Activity.